ИСТИНА

A state-of-art first principle calculation of the electronic structure of a alkali diatomics provides nowadays the transition dipole moment functions in a wide range of the internuclear distances with systematic errors which do not often exceed few percent [1]. This theoretical uncertainty is comparable or even better than accuracy of relative intensity measurements of laser-induced fluorescence (LIF) spectra recorded by Fourier transform (FT) spectrometer [2]. Furthermore, comprehensive deperturbation treatment of the excited states of alkali dimers performed in the framework of the rigorous coupled-channel approach allows one to represent energies and radiative properties of both local and regular perturbed rovibronic levels with experimental accuracy [3]. Aim of the present work was to calibrate the spectral sensitivity of FT spectrometer matching the relative intensity distribution measured in the long LIF progressions with their theoretical counterparts. In particular, the spectral sensitivity of the Bruker IFS-125HR FT spectrometer operated with InGaAs diode detector was determined in the near infrared region ν=8250-11700 cm-1 by a direct comparison of the calculated A1Σ+~b3Π→X1Σ+ rovibronic transition probabilities of KCs and K2 molecules with experimental relative intensity distribution in the relevant A~b→X laser induced fluorescence spectra [4]. The resulting graduate function S(ν) rapidly increases as ν increases according to the exponential fall of the InGaAs diode sensitivity at ν>10000 cm-1. We are planning to extend the calibration S(ν) function for low at ν<8000 cm-1 region by means of the measured and calculated (4)1Σ+→ A1Σ+~b3Π LIF spectra starting from the higher excited “shelf-like” state of the RbCs and KCs molecules. Moscow team thanks for the support by the RFBR grant No. 13-03-00446a. References 1. A-R Allouche and M. Aubert-Frecon, J. Chem. Phys. 136, 114302-15 (2012). 2. A. Jarmola, M. Tamanis, R. Ferber, E.A. Pazyuk, A.V. Stolyarov, J.Q.S.R.T. 95, 165-174 (2005). 3. A. Kruzins, I. Klincare, O. Nikolayeva, M. Tamanis, R. Ferber, E. Pazyuk, A. Stolyarov, J. Chem. Phys. 139, 244301-15 (2013). 4. A. Kruzins, I. Klincare, O. Nikolayeva, M. Tamanis, R. Ferber, E. Pazyuk, A. Stolyarov, in preparation